1. Field of the Invention
This invention relates to an electrophotographic copier in which an electrostatic latent image, formed on a photo-sensitive material, is developed with toner, and the developed image is transferred onto a transferring sheet to obtain a copied image. And more particularly, this invention relates to a cleaning unit in the copier which is adapted to remove toner and developing materials from the photo-sensitive material from which a developed image has been transferred.
2. Description of the Related Art
In general, in an electrophotographic copier, a predetermined electrostatic latent image is formed on a photo-sensitive material provided on a rotating photo-sensitive drum. The latent image is then developed with toner, and the developed image is transferred onto a transferring sheet to obtain a copied image. In general, after the developed image has been transferred onto the transferring sheet, the toner and developing materials remain on the photo-sensitive material necessitating removal from the photo-sensitive material with a cleaning unit.
A conventional cleaning unit, such as that shown in FIGS. 6, 7, and 8, has a housing 51 with an opening 51a. The opening 51a faces a photo-sensitive material 10a provided on the outer cylindrical wall of a photo-sensitive drum 10. A cleaning member, namely, a main blade 52 is disposed in the upper part of the housing 51 in such a manner as to touch the surface of the photo-sensitive material 10a in order to scrape the remaining toner and developing material off the surface of the photo-sensitive material 10a. A receiving blade 53 of thermo-plastic polyurethane rubber or similar material is provided in such a manner as to cover the lower portion of the opening 51a of the housing 51. The upper edge of the receiving blade 53 abuts against the photo-sensitive material 10a so that all of the toner and developing materials scraped off with the main blade 52 fall positively into the housing 51 without scattering therefrom.
If the electrophotographic copier is shipped out of the factory with the upper edge of the receiving blade 53 abutted against the surface of the photo-sensitive material 10a, then the surface of the photo-sensitive material 10a can deteriorate during transportation. The photo-sensitive material 10a is especially sensitive to deterioration when the copier is transported over a long distance with the environmental conditions changing greatly.
In order to overcome this difficulty, a method has been employed in which the electrophotographic copier is shipped out of the factory with the receiving blade 53 held away from the photo-sensitive material 10a. For instance, as shown in FIG. 9, the receiving blade 53 is coupled to a support 54 which can be detachably secured to the housing 51 of the cleaning unit, and when the copier is shipped out of the factory, the support 54 is disconnected from the housing 51 (as indicated by the two-dot chain line in FIG. 7). Accordingly, during the transportation of the copier, the receiving blade 53 does not contact the photo-sensitive material 10a and the photo-sensitive material 10a is less likely to be deteriorated.
This method is nevertheless disadvantageous because the receiving blade 53 is liable to be deformed. After transportation of the copier, the support 54 is coupled to the housing 51 so that the receiving blade 53 abuts the photo-sensitive 10a. However, the end portion of the receiving blade 53, being abutted against the photo-sensitive material 10a, is bent inwardly of the housing 51, thus forming a gap between the blade and the photo-sensitive material 10a as shown in FIG. 10. If a gap is formed, then when the toner is scrapped off with the main blade, it will drop through the gap, thus smudging the transferring sheet conveying path or some other part of the copier which extends below the housing 51.